Hello aspirant

Most of the students are start from 3rd year but I suggest you to start from your 2nd year is best so go for it and about preparation you can follow that:

Understand syllabus properly : You must be aware about the GATE syllabus, released by the organizing IIT. You must go through the section-wise and topic-wise syllabus of your chosen branch in order to know what all you have to study and what to avoid.

Solve previous year papers : Solving previous years papers is of utmost importance if you want to excel in the exam.

Weightage of Topics : it is advisable and important to study the complete GATE Syllabus, however, you can do a small exercise to gauge which sections, topics are much more important in terms of weightage given in GATE.

Resources other than books : It is good to look up topper and expert tips in this regard as they do mention the books or material they have referred to. Many GATE toppers run their own Facebook pages or blogs where they dispense advice and tips to wannabe GATE aspirants.

Hope this helps. All the best.